Here I am explain step-by-step
how to use WCF service and Linq to Sql in Windows Phone 7.
Go to the solution and add new WCF service application project.
![wcf project in window phone 7]()
Add a new item LINQ to SQL classes.
![linq to sql class in windows phone 7]()
Go to the server explorer and add Database and drag the table
![add database table in windows phone 7]()
View Service1.svc in browser.
![view service in browser]()
Add service reference to the project.
![add service reference in windows phone 7]()
Type the url and go select service and click on ok.
![add service reference in windows phone 7]()
Thank You....